import java.util.Scanner;

/**
 * @Title: 数的三次方根
 * @Author 贾金博
 * @Package PACKAGE_NAME
 * @Date 2024/3/3 19:46
 * @description: 二分
 */
public class 数的三次方根 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double x = sc.nextDouble();
        double l = -100;
        double r = 100;

        while(r - l > 1e-8) {
            double mid = (l + r) / 2.0;
            if(mid * mid * mid > x)r = mid;
            else if(mid * mid * mid < x)l = mid;
            else {
                l = mid;
                break;
            }
           // System.out.println("l = " + l + " r = " + r);
        }
        // 怎么保留小数
        System.out.printf("%.6f\n", l);
    }
}
